Flashing incandescent lamp



Dec. 10, 1968 o. M. GRIFFITH ET AL 3,416,029

FLASHING INCANDESOENT LAMP Filed March 29, 1966 2 Sheets-Sheet l I? WITNESSES 24 7o 28 INVENTORS M Dewey M. snffnhphorles W. Howkey and Victor K. Boughfon w. @M, ka/m AT TORN EY Dec. 10, 1968 D. MIGRIFFITH ET AL 3,416,029

FLASHING INCANDESCENT LAMP Filed March 29, 1966 2 Sheets-Sheet 2 United States Patent FLASHING IN CANDESCENT LAMP Dewey M. Griffith, Menlo Park, Charles W. Hawkey, Caldwell, and Victor K. Boughton, Pompton Plains, N.J., assignors to Westinghouse Electric Corporation,

Pittsburgh, Pa., a corporation of Pennsylvania Filed Mar. 29, 1966, Ser. No. 538,252

7 Claims. (Cl. 31572) ABSTRACT OF THE DISCLOSURE A flashing incandescent lamp in which the filament is mounted between a first lead-in conductor and a thermostatic element. A second V-shaped lead-in conductor contacts the thermostatic element and applies sufficient pressure to that element to maintain a predetermined deflection of the thermostatic element when the lamp is cold.

This invention relates to flashing incandescent lamps and more particularly to the filament mount structure of such a lamp.

Considerable difficulty has been encountered in attempting to manufacture, on a production basis, flashing incandescent lamps which have consistent flashing rates within acceptable tolerances, as for example 100*160 flashes per minute. A particular problem with this kind of miniature incandescent lamp is the no light or stay light, the no light being a condition where the lamp does not light at all, as opposed to the stay light where the lamp remains lighted and does not flash.

It has been a common practice where the filament is mounted between one lead-in conductor and a thermostatic or bimetal strip to preform the other lead-in conductor to its final shape and then subsequently place it against the bimetal to establish the required tension or deflection. In construction of this nature, since the establishment of uniform tension between the bimetal and the deflecting lead-in conductor is critical to uniform flashing rates, bimetal springback against the deflective action of the lead-in conductor is an important factor. Attempts to unify the tension between the bimetal and the lead-in conductor have been accomplished by mechanically displacing the bimetal, then placing the lead-in conductor in front of the bimetal and releasing the bimetal against the lead-in conductor. This method of production has proved unsuccessful in producing lamps having a uniform flashing rate and has resulted in a substantial loss of finished larnps due to their failure to comply with established standards, such as automotive standards, for acceptable flashing rates.

It has been found that lead-in conductor to bimetal tension determines the flashing rate of miniature flashing incandescent lamps to a greater degree than any other variable and therefore this tension or more particularly the initial deflection and springback of the bimetal must be controlled. The present invention provides a flashing incandescent lamp of extremely uniform flashing rates by providing a preshaped lead-in conductor adjacent to a flexible bimetal strip which supports and is electrically connected to one end of a conventional lamp filament, positioning an angular backup plate adjacent to the bimetal strip and applying a predetermined force normal to the upper portion of the preformed lead-in conductor to cause the upper end of said lead-in conductor to force the bimetal against the backup plate causing a predetermined deflection of the bimetal strip, said predetermined force also providing a permanent set in the lead-in conductor to maintain a predetermined deflection of said bimetal and preventing any springback of the bimetal from its defiected position. By placing this permanent set or kink in the lead-in conductor the problems of bimetal springback are thus eliminated.

An object of the present invention is to provide miniature flashing incandescent lamps having substantially uni form flashing rates.

Another object of the present invention is to provide a lead-in conductor configuration that will provide consistency of bimetal displacement in a flashing incandescent lamp.

These and other objects as well as many of the attendant advantages of the present invention will become more readily apparent as the following detailed description is considered in conjunction with the accompanying drawings, in which:

FIGURE 1 is a side elevation view of a filament mount prior to tension setting;

FIG. 2 is a front elevation view of a filament mount prior to tension estting;

FIG. 3 is a side elevation view of a filament mount after the tension has been set;

FIG. 4 is a front elevation view of a filament mount after tension has been set;

FIG. 5 is a fragmentary elevational view, partly in section, of the tension setting apparatus used in performing the method of the present invention;

FIG. 6 is a fragmentary elevational view of the tension setting apparatus in a first position;

FIG. 7 is a fragmentary elevational view of the tension setting apparatus in its crimping position;

FIG. 8 is an exploded view of the bimetal backup plate and rear stop mechanism of the tension setting apparatus; and

FIG. 9 is an elevation view, partly in section, of a flashing incandescent lamp employing the filament mount of the present invention.

Referring now in detail to the drawings, wherein like reference characters represent like parts throughout the several views, there is shown in FIGS. 1 and 2 the preformed filament mount generally designated 10 including a conventional supporting insulator or glass bead 12 having a pair of lead-in conductors 14 and 16 extending therethrough. A thermostatic metal element 18 is positioned approximately midway between the two lead-in conductors substantially along a line defined by the intersection between each lead-in conductor and the glass bead. The thermostatic element 18 extends at an angle of about 68 with the upper surface of the glass bead and lies behind the upper portion of lead-in conductor 16 as shown in FIGS. 1 and 2. The thermostatic element 18 is preferably a bimetal strip conventionally constructed of Invar and silver with the Invar side to the rear and the silver side facing lead-in conductor 16. The lead-in conductor 16 in its preformed condition, as best shown in FIG. 1, extends vertically from the glass bead for about one-sixth of its extended length then bends at about 60 from the vertical for about one-third of its extended length, then bends at 16a at an angle of approximately with respect to the last mentioned third back toward the vertical for approximately another one-third of its extended length, then proximate to its extremity at 16b it bends 90 in a direction away from the plane of the bimetal.

After the filament mount is formed with its lead-in conductors 14 and 16 and bimetal 18 in the positions shown in FIGS. 1 and 2 a force is applied to lead-in conductor 16 at approximately the point 16c (see FIG. 3) causing the point 16b to contact the bimetal and deflect it a predetermined distance. The force applied at causes leadin conductor 16 to bend at an angle or elbow 16a a suflicient distance to provide a set or kink in the lead-in conductor at that point which maintains the bimetal 13 in the predetermined deflected position. After a force has been applied to lead-in conductor 16 at point 160 the lead-in conductors and bimetal 18 will maintain the relationships and shapes shown in FIGS. 3 and 4. The two significant changes which occur in lead-in conductor 16 from that shown in the FIG. 1 position are: (l) the angle or elbow at 16a defined by the two longer sections of the lead-in conductor is now approximately 60 as opposed to the 90 angle of FIG. 1 and, (2) the radius of curvature of the bend or elbow at 16a is increased slightly due to the rolling effect as the kink or set is established. The novel filament mount structure shown in FIGS. 3 and 4 provides for a comparatively uniform flashing rate in miniature flashing incandescent lamps by providing a fixed and substantially uniform minimum deflection of bimetal 18 due to the comparatively unyielding tension applied thereto by the permanent set, crimp or bend applied to lead-in conductor 16 at bend or elbow 16a.

FIGS. 5 to 8 inclusive, represent a mechanism for providing for the uniform deflection of bimetal strip 18 and the substantially constant configuration for lead-in conductor 16. A filament mount is constructed on a conventional flashing miniature mount machine and is carried by an indexing head 24 during the assembly thereof. After the filament mount has been assembled the head 24 is indexed to a position shown in FIG. 5 with the filament mount constructed as shown in FIGS. 1 and 2. At this position the filament mount 10 is acted upon by the tension setting mechanism generally designated 26. The tension setting mechanism 26 includes a base 28 which carries a rotatable pinion gear (not shown) and a pair of associated racks 30 and 32. The racks 30 and 32 carry filament mount support jaws 34 and 36 respectively and are operable in response to rotation of the pinion gear to move the support jaws 34 and 36 in opposite directions to the positions shown in FIG. 6 to support the lower half of the lead-in conductor 16. A bimetal backup plate 38 is also carried by rack 30. The position of the backup plate 38 with respect to the position of the filament mount carried by indexing head 24 is completely adjustable to control the deflection of bimetal 18 during the tension setting operation.

The adjustable backup plate assembly as can best be seen by reference to FIG. 8, generally includes a base member 40 which is adjustably secured to rack 30 by means of a bolt and slot connection at 42. This bolt and slot connection provides for the vertical adjustment of both the backup plate 38 and the support jaw 32. Within the cutout portion 44 of base member 40 is mounted a yoke 46 which is adjustably secured to base member 40 by bolt 48. Slot 50 in yoke 46 through which bolt 48 extends allows for the horizontal adjustment of yoke 46 toward or away from the vertical plane of the filament mount. Bimetal backup plate 38 is carried by a rocker arm 52 and includes a pair of threaded adjustment bolts 54 and 56. The bimetal backup plate through rocker arm 52 is rotatably mounted within a cutout portion of I yoke 46 by means of a pin 58 and secured therein by a cover plate 62 which overlies cutout portion 60 and is threadedly secured by means of a bolt 64 to the yoke 46. Adjustment bolts 54 and 56 coact with cover plate 62 and yoke 46 respectively to accurately position bimetal backup plate 38 angularly about pivot pin 58 to accurately control the degrees of deflection imparted to bimetal 18 by tension setting tool 66.

A tension setting tool head 68 is pivotally mounted at 70 to base 28 and has adjustably secured therein the tension setting tool 66. The tension setting tool 66 has a bifurcated probe 72 which receives lead-in conductor 16 when the head 68 is actuated. Tension setting tool 66 is adjustably mounted within head 68 by means of a tap screw 74 which serves to adjustably position the tool 66 toward or away from the point of contact with lead-in conductor 16 and thus accurately controls the force imparted thereto. At its upper end the head 68 carries a roller 76 which coacts with a cam surface 78 on the leading end of actuating bar 80. Actuating bar 80 is sequentially operated by means of a cam mechanism (not shown) to force the head 68 to pivot about the pivot 70 to set the .tension in lead-in conductor 16 through tool 66. A spring 82 secured at one end to head 68 and at its other end to base member 28 serves to hold roller member 76 in continuous contact with cam surface 78.

In operation an indexing head 24 carrying a filament mount 10 is indexed to the position shown in FIG. 5. The pinion (not shown) operates to move racks 30 and 32 to the position shown in FIG. 6, thus placing support jaws 34 and 36 in a position to support the lower half of the filament mount structure. Bar 80 is then operated by its actuating mechanism (not shown) to pivot tool carrying head 68 about the pivot 70 to cause tension setting tool 66 to move to the position shown in FIG. 7 forcing bimetal 18 against bimetal backup plate 38. At this point a slight further motion of tool 66 causes a set or crimp at the elbow 16a of lead-in conductor 16 which prevents springback by bimetal 18 when the tension setting tool is removed. Carriage 68 is then returned to its FIG. 6 position and the support jaws moved to their FIG. 5 position permitting the indexing out of the mount carrying head 24.

It has been found that by employing the structure and method according to the present invention that a miniature flashing incandescent lamp utilizing a Thermostat metal (Invar and silver) bimetal 0.005 inch thick and extending 5 mm. above the glass bead which is contacted at 3.5 mm. above the bead by the curved lead-in conductor with a contact pressure of from about 6 to 8 grams will consistently produce flashing rates in the lamp between and flashes per minute which is well within established requirements, such as used in the automotive industry.

The filament mount structure can, of course, be employed in any of the many different bulb shapes and base configurations available in the art. However, for purposes of illustration, the typical automotive type bayonet base has been shown in FIG. 9 and includes a light transmissive bulb portion 86 and metal shell base 88 having bayonet protuberances 90 to secure the base in a complementary socket. One lead-in conductor, for example lead-in conductor 14, is connected to a metal end contact eyelet 94 and the remaining lead-in conductor, for example lead-in conductor 16, is connected to a metal side shell contact 96 in the conventional manner.

As can be seen from the foregoing the present invention provides a lead wire to bimetal contact which can be uniformly set and will produce a comparatively consistent flashing rate in a miniature flashing incandescent lamp. It has further been shown that the invention accurately determines the position of the lead with respect to the bimetal, and therefore accurately determines the lead to bimetal tension which is a critical factor in controlling flashing rates in flashing incandescent lamps.

Since numerous changes may be made in the above described apparatus and different embodiments of the invention may be made without departing from the spirit thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A flashing incandescent lamp having a base portion and a bulb portion, and a filament mount therein, said filament mount comprising:

(a) a supporting insulator;

(b) a pair of lead-in conductors in contact with said base portion and extending through said supporting insulator;

(c) a thermostatic element mounted in said supporting insulator and extending substantially in a common plane with one of said lead-in conductors and located adjacent the other of said lead-in conductors; and

(d) a filament mounted between one end of said one conductor and an end of said thermostatic element,

said other lead-in conductor having a substantially V-shaped bend therein lying in a plane substantially perpendicular to said common plane and contacting said thermostatic element to provide a predetermined deflection in said element whereby upon operation of said lamp said element will alternately make and break contact with said other leadin conductor to cause said lamp to flash at a predetermined rate.

2. A flashing incandescent lamp according to claim 1, wherein said other lead-in conductor applies a pressure of about 6 to 8 grams to said thermostatic element.

3. A flashing incandescent lamp according to claim 1, wherein said other lead-in conductor extends in a direction parallel to the plane of said thermostatic element for approximately one-sixth of its length, then first bends at an angle of approximately 60 away from said plane for onethird of its length, then secondly bends back toward said plane at an angle of about 60 for approximately onethird of its length, and thirdly bends away from said plane for approximately one-sixth of its length at an angle of about 60.

4. A flashing incandescent lamp according to claim 3, wherein said other conductor contacts said thermostatic element at its third bend.

5. A flashing incandescent lamp according to claim 1, wherein said other lead-in conductor includes a first bend 6 away from the plane of said thermostatic element, a second V-shaped bend toward the plane of said thermostatic element, and a third bend away from the plane of said thermostatic element.

6. A flashing incandescent lamp according to claim 5, wherein said V-shaped bend subtends at an angle of approximately forming a permanent set in said other lead-in conductor and said other lead-in conductor contacts said thermostatic element at said third bend.

7. A flashing incandescent lamp according to claim 1, wherein said V-shaped bend defines an acute angle.

References Cited UNITED STATES PATENTS 2,361,486 10/1944 Macgregor 315-73 X 2,901,667 8/1959 Kotsch et a1. 315--72 3,082,349 3/1963 Zecca et a1. 315-73 X 3,122,675 2/1964 Lonn et al. 315-74 X JOHN W. HUCKERT, Primary Examiner. A. J. JAMES, Assistant Examiner.

US. Cl. X.R. SIS-73, 74, 313331 

